Exemplary embodiments of the present invention relate to a fiber application tool for a fiber application process having a fiber contact surface area, which has a fiber contact surface for contacting fibers for the purpose of redirecting and/or pressing fibers for application onto a work surface and having an activation device for activating an adhesive, matrix, resin, or binder material provided at the fibers by means of an activation radiation so that the fibers are tacked onto the work surface. Furthermore, the exemplary embodiments relate to a fiber placement device for, preferably, automatically carrying out a fiber placement method having such a fiber application tool. Furthermore, the exemplary embodiments relate to a fiber placement method and a production method for producing work pieces made up of fiber-reinforced material by using such a fiber placement method.
A preferred field of application of a fiber application tool according to the present invention are automatic fiber placement methods, known as “Automatic Fiber Placement” (AFP).
Such fiber application tools, fiber placement devices, and respective fiber placement methods suitable for AFP are, for example, known from the following Internet videos:                http://www.youtube.com/watch?v=-qAaJwm11dg, published on 14 Nov. 2011;        http://www.youtube.com/watch?v=DV1n35pabXs, published on 3 May 2013;        http://www.youtube.com/watch?v=QDbrVTWnFIU, published on 3 Jan. 2009.        
Examples from the patent literature for such fiber application tools and fiber placement devices suitable for automatic fiber placement are described and shown in EP 0 491 353 A1 or EP 2 882 681 A1.
In an automatic fiber placement method, fibers are unwound from a spool or the like, which are situated in the area of a head of a motion apparatus—for example, a robotic arm—and are applied in a desired orientation and arrangement onto a work surface by a fiber application tool in the form of a fiber application roller or compaction roller. For this purpose, an outer circumferential area of the roller serves for redirecting, applying, and pressing the fibers. In addition to a fiber delivery device for delivering continuous filaments or fiber material bands, the fiber application tool, a cutting device for cutting fibers and, furthermore, an activation device are thus also provided at the placement head. In order for the fibers to tack to the work surface, the fiber material is provided with a binder or resin or the like, and this adhesive material may be, for example, activated by heat or activation radiation, so that a tacking of the placed fibers results. These activation devices are also carried along at the head.
Accordingly, in fiber placement, energy sources—so-called activation units or activation devices—are, as a function of the used material, used for starting to melt the binder or the resin on the fiber material. The fiber material having the partially molten binder or partially molten resin is then pressed by a roller onto the work surface—for example, a tooling. In this instance, a compaction also occurs. Pressure and activation have to be adjusted in such a way that the fiber material is affixed to the tooling. The activation unit has to heat-up the fiber material as quickly as possible to the required temperature so that it is sufficiently molten at the time of compaction.
As it is know from the aforementioned related art, the following methods are established for activation:                Laser for heating the tooling—i.e., the work surface—before the roller;        Infrared for heating the tooling—i.e., the work surface—before the roller;        A heated roller for directly activating the binder or the resin; or        Hot gas for activating the binder or the resin and for pre-heating the tooling or the work surface.        
Accordingly, the placement head moved by the motion apparatus also carries the activation units; for this purpose, for example, an activation device for emitting activation radiation—laser radiation or LED infrared light or the like—is situated on the work surface for pre-heating the same.
The known fiber placement devices thus have a very bulky and heavy placement head. In the case of a heated roller, a targeted activation and handling is difficult. Altogether, the known placement method uses a relatively large amount of energy for the activation.
The present invention improves, in particular, AFP but also other fiber placement methods having activatable binders or similarly suited fiber placement devices and fiber placement methods.
For this purpose, the present invention suggests a fiber application tool, a fiber placement device, a fiber placement method, and a production method according to the independent claims.
Advantageous refinements of the present invention are the subject of the dependent claims.
According to a first aspect, the present invention provides a fiber application tool for a fiber placement process—in particular, for a fiber placement method or AFP method—having a fiber contact surface area, which has a fiber contact surface for contacting fibers for the purpose of redirecting and/or pressing fibers for application onto a work surface and having an activation device for activating an adhesive, matrix, resin, or binder material provided at the fibers by an activation radiation for affecting a tacking of the fibers onto the work surface, and the fiber contact surface area is transparent for the activation radiation and the activation device is designed and devised in such a manner that the activation radiation is guided and/or delivered through the transparent fiber contact surface area to the fibers to be pressed by the fiber contact surface.
“Fibers” refer to fiber materials in different forms, also in form of fiber bands or fiber fabric bands or the like.
It is preferred that the fiber contact surface is formed at the circumference of a fiber application and/or compaction roller; that at least one circumferential surface area, having the fiber contact surface, of the fiber application and/or compaction roller is designed in a transparent manner; and that the activation device is designed and devised for guiding the activation radiation starting from the interior of the fiber application and/or compaction roller through the transparent circumferential area to the fibers to be activated, which contact the circumferential surface area according to the specified usage.
It is preferred that a circumferential partition of the fiber application and/or compaction roller made up of transparent material, which forms the fiber contact surface area or surrounds the fiber contact surface at the outer circumference in form of a cylinder barrel, is made out of transparent plastic and/or glass.
It is preferred that the fiber application and/or compaction roller has an inner bearing segment not rotatable relative to a placement head or the like, which is to be mounted at a motion apparatus for relatively moving across the work surface, and a tubular body or roller body, at least partially made up of transparent material, which is rotatable relative to the bearing segment and surrounds the bearing segment at the circumference, and the activation device is situated at the inner bearing segment.
It is preferred that the activation device is designed and devised in such a manner that the activation radiation is guided through the transparent circumferential area into an angular range, in which fiber is redirected at the roller and which is located in rotational direction in front of the contact area, where the fiber is applied upon contact.
In one possible refinement it is preferred that the activation device has an interior light source and/or an interior LED in the fiber application tool for delivering the activation radiation. In this manner, the activation radiation may be produced in the interior of the fiber application tool.
Alternatively, it is preferred that the activation device uses an external radiation source for the activation radiation, for example, an external light source and/or an external LED, by which the activation radiation, for example, the light radiation may be produced outside of the fiber application tool, and a guiding device for guiding the activation radiation from the radiation source into the interior of the fiber application tool. The guiding device may have a light conducting device, for example, a glass fiber or a light conductor. The light conducting device may also include a light path having a deflection mirror or the like. This option enables to easily access the radiation source and is less restricted in regard to dimensions; however, a very compact fiber application tool delivering the radiation from the interior through the transparent fiber contact surface is possible.
Under both options of internally and externally producing radiation, the activation device may have a focusing device for focusing the activation radiation onto or near the outer surface of the fiber contact surface area forming the fiber contact surface. A focusing device is then advantageous if the radiation intensity is relatively low. If a high radiation intensity may be generated in the area of the fibers, a focusing may be foregone.
It is preferred that the focusing device has at least one focusing lens to directly irradiate the fibers that are in contact with the fiber contact surface through the transparent fiber contact surface area.
It is preferred that the distances between the light source and/or the LED on the one hand and the at least one focusing lens on the other are chosen in such a manner that the focus point is located directly on the fiber contact surface. Alternatively, the light source energy is chosen high enough so that a focusing is not necessary.
It is preferred that the internal light source and/or LED and/or the focusing device and/or an outlet of the radiation guiding device are situated in the fiber application and/or compaction roller.
According to a further aspect, the present invention provides an automatic fiber placement device for automatically placing fibers onto a work surface, including:
a fiber delivery device for delivering fibers, in particular, in the form of continuous filaments unwinding from a fiber spool or in form of a fiber band or fiber material band;
a fiber application tool according to one of the preceding refinements;
a cutting device for cutting the fibers to a desired length;
and a motion apparatus for moving the fiber application tool relative to the work surface to apply and press the fibers delivered by the fiber delivery device onto the work surface.
According to a further aspect, the present invention provides a fiber placement method for automatically placing fibers onto a work surface, including:                a) Applying and pressing fibers provided with adhesive, binder, matrix, or resin material by a transparent fiber contact surface; and        b) Guiding activation radiation through the fiber contact surface for activating the adhesive, binder, matrix, or resin material.        
It is preferred that step b) occurs before step a).
It is preferred that step a) includes:
Applying and pressing fibers using a fiber application and/or compaction roller, which has at least one transparent circumferential surface area; and
that step b) includes:
Guiding the activation radiation through the transparent circumference area.
Preferably, the following step is provided: delivering fibers to the fiber application and/or compaction roller and redirecting fibers at a fiber contact surface designed for redirecting until contact with the work surface is established, and the activation radiation in the area for redirection is guided prior to contacting the work surface through the fiber contact surface and onto the fibers.
According to a further aspect, the present invention provides a production method for matrix composite work pieces, including the steps:
Producing a preform by carrying out an automatic fiber placement method according to one of the preceding embodiments; and
Producing the work piece from the preform.
In a particularly preferred embodiment of the present invention, a compaction roller or a miscellaneous fiber application roller is equipped with an internal light source in form of an LED and possibly with a focusing lens to radiate the fiber directly. In this instance, the roller is made up of a transparent material and has a respective roller element made up of such transparent material. The distances between the lenses and the LED are preferably adjusted in such a manner that the focus point is directly located on the surface of the roller. Since the fibers are directed across the surface, they are situated directly in the focus point.
Some advantages of preferred embodiments of the present invention are:                a compaction roller remains cold on the outside;        the activation unit or activation device is very compact in comparison to other solutions;        a light emission of the fiber placement device is very low;        a light source is well and quickly regulated;        when using a binder for laying down, not the binder but the fiber is radiated.        
A low light emission of the system is very advantageous, in particular, in systems having optical in-line quality control.
A quick and simple regulation of the light source is particularly advantageous owing to the adaptation to the lay-down speed.
Altogether, a device for applying fibers that is very compact, energy optimized, and also optimized from a process engineering viewpoint and a respective fiber placement device are created.